Isotetralin, or 1,4,5,8-tetrahydronaphthalene, is a known material. It is known to be produced by reduction of naphthalene using sodium in liquid ammonia. Electrochemcial reduction of naphthalene to produce 1,4-dihydronaphthalene with minor amounts of tetralin, or 1,2,3,4-tetrahydronaphthalene, is described in U.S. Pat. No. 3,699,020. The solvent-electrolyte system used in this prior process was a mixture of diethylene glycol dimethyl ether, water, tetrabutyl ammonium bromide and ammonia. The electrochemical reduction of benzene to produce 1,4 cyclohexadiene in a solvent-electrolyte system of hexamethylphosphoramide, lithium halide and an alcohol is disclosed in U.S. Pat. No. 3,492,207. When this system was used with napthalene it produced only tetralin. There is no previously known electrolytic reduction process for production of isotetralin.